also quote key names when outputting json
also quote key names when outputting json

In normal situations when exporting json a key shouldn't need to
be quoted, but sometimes user-provided data is serialised, for example
tags from taglib take both the key and value. On flac files this key
can be user-provided and therefore a bad key can create invalid json

mrgloom/essentia,arseneyr/essentia,CompMusic/essentia,milrob/essentia,GiantSteps/essentia,NadineKroher/essentia,sankalpg/Essentia_tonicDebug_TEMP,milrob/essentia,ChristianFrisson/essentia,soundcloud/essentia,GiantSteps/essentia,NadineKroher/essentia,mrgloom/essentia,jjaner/essentia-musicbricks,GiantSteps/essentia,ChristianFrisson/essentia,jjaner/essentia-musicbricks,mrgloom/essentia,GiantSteps/essentia,jjaner/essentia-musicbricks,CompMusic/essentia,soundcloud/essentia,GiantSteps/essentia,milrob/essentia,mrgloom/essentia,carthach/essentia,CompMusic/essentia,mrgloom/essentia,MTG/essentia,MTG/essentia,sankalpg/Essentia_tonicDebug_TEMP,ChristianFrisson/essentia,GiantSteps/essentia,MTG/essentia,sankalpg/Essentia_tonicDebug_TEMP,MTG/essentia,MTG/essentia,arseneyr/essentia,soundcloud/essentia,carthach/essentia,ChristianFrisson/essentia,ChristianFrisson/essentia,carthach/essentia,CompMusic/essentia,NadineKroher/essentia,milrob/essentia,NadineKroher/essentia,sankalpg/Essentia_tonicDebug_TEMP,carthach/essentia,carthach/essentia,soundcloud/essentia,arseneyr/essentia,arseneyr/essentia,soundcloud/essentia,soundcloud/essentia,jjaner/essentia-musicbricks,NadineKroher/essentia,sankalpg/Essentia_tonicDebug_TEMP,jjaner/essentia-musicbricks,arseneyr/essentia,sankalpg/Essentia_tonicDebug_TEMP,milrob/essentia,CompMusic/essentia